Knoevenagel condensation of cyclic ketones with benzoylacetonitrile and N,Nâ²-dimethylbarbituric acid. Application of sterically hindered condensation products in the synthesis of spiro and dispiropyrans by hetero-Diels-Alder reactions
Keywords: Spiro compounds; Hetero-Diels-Alder reactions; 1-Oxa-1,3-butadienes; Uracils;